The present invention relates to voltage surge arresters and particularly to a polyphase secondary arrester for protecting electrical equipment.
With the advent of sintered metal oxide varistors, particularly zinc oxide varistors, more complete protection of electrical equipment from the harmful consequences of voltage surges or transients is now possible. This is due to the exceptionally high nonlinear resistance characteristics of zinc oxide, which permits the elimination of spark gaps required of silicon carbide varistors commonly used in the past. Absent spark gaps, metal oxide varistors can be tailored to suppress lower levels of voltage surges which are nevertheless potentially damaging to electrical motors, appliances and the like. Moreover, the elimination of spark gaps significantly simplifies the design and manufacture of surge arresters.
It is accordingly an object of the present invention to provide an improved polyphase voltage surge arrester.
A further object is to provide a voltage surge arrester of the above character which is exceptionally compact in size.
An additional object is to provide a secondary voltage surge arrester of the above character which is efficient in design, convenient to manufacture and install, and reliable in service.
Other objects of the invention will in part be obvious and in part appear hereinafter.